The present invention generally relates to processing of images, and in particular to an image reading and recording apparatus having a unitary read/write head in which a sensor array for reading an image from a document and a thermal head for recording an image on a sheet are assembled as a unitary body.
In the image reading/recording apparatus for reading an image from a document and for recording an image on a sheet such as a facsimile, various efforts are made to design the size of the apparatus compact. Such an effort includes use of various mechanisms and parts in common by the image reading part and image recording part. For example, the inventors of the present invention have previously proposed such an image read/write apparatus in the Japanese Laid-open Patent Application 62-112465.
In the foregoing conventional apparatus, the proximity sensor array for reading an image from a document by contacting therewith is assembled together with a thermal head for recording an image on a sheet as a unitary head body, and there is provided a feed roller in the vicinity of the head body for feeding the sheet or document. When reading a document, the feed roller is displaced to a position close to the sensor array while when recording an image on a sheet, the feed roller is displaced to a position close to the thermal head. For this purpose, the apparatus has a mechanism for displacing the feed roller.
In this conventional apparatus, it is necessary to provide the mechanism for effecting the desired displacement of the feed roller. In addition, such a system requires a control unit for controlling the displacement of the feed roller. Obviously, these mechanism and control unit need a space, and therefore, the construction of this conventional apparatus is not advantageous in view point of reducing the size of the apparatus.
Further, the conventional apparatus has a problem of accumulation of heat in the apparatus, as the sensor array and the thermal head are disposed close with each other. It should be noted that the thermal head produces heat at the time of recording. With the accumulation of heat, the temperature inside the apparatus rises excessively and various problems occur particularly in the operation of the sensor array or even in the operational characteristic of the thermal head itself. For example, the input-output characteristic of the sensor array may be changed upon the rise of the temperature, or the value of resistors used in the thermal recording head for setting the recording pulse widths optimum may be deviated from the nominal value. In the latter case, the carefully determined setting of the resistance values for achieving a uniform recording characteristic over the entire recording surface of the sheet may be changed. Thereby, one has to readjust the value of the resistors individually while monitoring the state of the recorded images. However, such an adjusting procedure requires a repetition of recording and adjustment and hence a considerable time of operator.